The present invention relates to a Diesel smoke meter which measures an amount of carbon contained in exhaust gases of the Diesel engine to find a density of black smoke.
In view of resource conservation as well as public safety, it is necessary to detect black smoke discharged from the Diesel engine to maintain the combustion of the engine in an optimum condition. It has been eagerly desired to develop a compact smoke meter which is high in precision and is suitably mounted on a vehicle.
As a smoke meter of this kind, it has been heretofore known to use a photo-system wherein light emitted from a light source is transmitted into the exhaust gas or reflected therein, and the amount of carbon in the exhaust gas is measured by the intensity of transmitted light or reflected light received by a light receiving means.
However, in the photo-system smoke meter just described, there arises the problem that when carbon particles adhere to the light source, the accuracy of the light receiving means or windows which are provided in the exhaust gas pipe line to transmit light, deteriorates. To prevent this problem, it has been necessary to spray clean air against the window or to perform maintenance frequently.